Type 1 (juvenile) diabetes is an organ-specific autoimmune disease resulting from destruction of insulinproducing pancreatic beta-cells. In non-diabetics, islet cell antigen-specific T cells are either deleted in thymic development or are converted to T regulatory cells that actively suppress effector responses to islet cell antigens. In juvenile diabetics and in the NOD mouse model of juvenile diabetes, these tolerance mechanisms are missing. In their absence, islet cell antigens are presented by human leukocyte antigen (HLA) class I and II molecules and are recognized by CD8(+) and CD4(+) auto-reactive T cells. Destruction of islet cells by these auto-reactive cells eventually leads to glucose intolerance. Modulation of auto-immune responses to autologous epitopes by induction of antigen-specific tolerance may prevent ongoing beta-cell destruction. EpiVax, Inc. has identified a set of natural T regulatory epitopes that induce tolerance to immunogenic proteins. Preliminary studies demonstrate that these "Tregitopes" specifically induce natural Tregs and, when coadministered with an antigen, lead to expansion of antigen-specific regulatory T cells. Initial studies have demonstrated tolerance induction in the context of dust-mite allergy. The goal of this Phase I SBIR application is to evaluate whether immune response to islet cell antigens can be redirected by administration of Tregitopes in conjunction with T1D antigens, leading to "antigen-specific adaptive tolerance induction" (T1D ASATI) in a murine model of T1D. The outcome of T1D ASATI will be measured in terms of regulatory T cell responses to preproinsulin (PPI) T-cell epitopes in vivo and in vitro. In the context of this application we will: (1) Assess whether Tregitopes suppress the PPI-specific response ex vivo using PBMC from recent-onset type 1 diabetics, (2) Measure Tregitope-induced modulation of T1D pathology and PPI-specific immune responses in NOD mice and (3) Elucidate the mechanism of Tregitopeinduced PPI ASATI in DR4 transgenic mice. If successful, this research and development program will lead to a clinical approach that will generate or restore tolerance in juvenile diabetics. PUBLIC HEALTH RELEVANCE: This research will investigate an immune treatment that may slow the progression of Type 1 (juvenile) diabetes.